The present invention is directed to refrigeration systems and more particularly to a single liquid line service and process device combining a refrigerant filter, an access port, a flow controller and a moisture indicator.
In refrigeration systems, a heat exchanger such as an evaporator transfers heat from a first fluid such as air to a refrigerant in the evaporator. Absorbing the transferred heat from the first fluid vaporizes the refrigerant. The vaporized refrigerant is delivered via a suction line to a compressor where the compressor increases the pressure of the refrigerant vapor to a point where its condensing temperature is above the temperature of water available for condensing purposes. The pressurized refrigerant vapor is passed from the compressor via a hot gas line to a condenser where the heat contained in the pressurized refrigerant vapor is transferred to another cooler medium such as water. The vapor condenses back to a liquid refrigerant during this process and passes along a liquid line through an expansion valve back to the evaporator. The expansion valve separates the high pressure part of the system maintained by the compressor from the low pressure part of the system where refrigerant is vaporized by allowing only as much liquid to pass through the expansion valve as the evaporator can vaporize.
A number of devices are provided in the liquid line between the condenser and the expansion valve to control and maintain the refrigeration system. These devices generally include, in order from the condenser, a liquid line shutoff valve, an access port generally used to charge the refrigeration system, a filter/drier to remove contaminants and moisture from the refrigerant, and a moisture indicator such as a sight glass to monitor refrigerant state which indicates loss of charge or clogging of the filter/drier.
In the past, four separate devices have been required to provide these four separate functions. Combining these previously distinct elements into a single device provides substantial advantages in the form of inventory control and management, as well as in reducing the physical dimensions and number of connections in the liquid line. Additionally, maintenance of a single device is generally much easier than maintaining multiple distinct devices.
A number of previous patents have attempted to combine several of these elements into a single device but none has been able to combine all four into a single device. For instance, U.S. Pat. No. 4,018,061 shows a filter/drier which includes a sight glass and an expansion valve. U.S. Pat. No. 4,528,826 and U.S. Pat. No. 4,474,034 each disclose the combination of a charge port, a drier/filter, and a sight glass. U.S. Pat. No. 4,614,087 discloses a filter/drier in combination with a high pressure safety switch and a sight glass. However, none of these patents have been able to combine a filter/drier, a charge port, a refrigerant flow control and a moisture indicator into a single device.